The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
There are generally two kinds of power architectures for telecom and computing applications: centralized power architecture and decentralized power architecture. A centralized architecture is a power system in which all power related functions, from input power to generation of the DC circuit voltage, are contained within one physical area. A decentralized power architecture (also referred to as distributed power architecture) is a power system that is functionally and physically partitioned such that the final stage of power processing is located in correspondence to load functions and/or packaging. Decentralized power architectures can provide certain electrical performance advantages over centralized power architectures. In a decentralized architecture, the DC distribution system becomes much shorter and simpler, thereby eliminating power losses in the distribution network. Better dynamic response performance is also achieved due to the lower inductance between converters and their loads. Other advantages include distributed heat load, enhanced reliability, and lower total cost. The centralized power architecture is becoming less common in today's electronic systems.
One of the most dominant decentralized architectures, referred to as “on-board-power,” provides the dc-dc conversion function on each board. In such a system, the dc-dc power converters essentially become components on the circuit boards, and the diffused nature of power dissipation allows for a large amount of flexibility in the electrical and cooling system design.
There are two primary categories of decentralized power architectures for telecom and datacom applications: distributed power architecture (DPA) and intermediate bus architecture (IBA). A DPA power system is illustrated in FIG. 1 and indicated generally by reference numeral 100. In the example of FIG. 1, a 48V bus 102 supplies a load board 104, and dc-dc converters 106, 108 and 110 are located close to the load circuitry. A first regulated dc-dc converter 106 supplies a first load 112 and a non-isolated (NI) dc-dc converter 110 supplies a second load 116. Unlike an isolated converter, the input and output of an NI converter share a common ground. A second regulated dc-dc converter 108 supplies a third load 114. Each dc-dc converter in the system is regulated by a digital or analog controller integrated within such dc-dc converter. A power manager 118 is implemented using one of, or a combination of, a dedicated integrated chip, an FPGA and a microprocessor. The function of the power manager/supervisor may include monitoring, sequencing, and margining. In addition, the power manager may communicate with load circuitry on the load board and with other systems beyond the board via a communication bus 120.
FIG. 2 illustrates an intermediate bus architecture (IBA) power system 200. Instead of directly supplying loads like the regulated converters 106 and 108 shown in FIG. 1, a bus converter 202 operating at open loop provides an unregulated intermediate bus voltage to three cascaded secondary-stage NI dc-dc converters 204, 206 and 208 that are mounted physically close to load circuitry on a load board 210. Each of the dc-dc converters 204, 206 and 208 supplies a voltage directly to one of a first load 212, a second load 214 and a third load 216, respectively, and is regulated by a digital controller integrated within such dc-dc converter. A power manager 218 has the same functionality as the power manager 118 of FIG. 1. This architecture is generally simpler and more flexible than the DPA.
As the number of supply voltages continues to increase, the number of analog integrated circuits needed to monitor, sequence, and margin them also increases. As a result, costs rise and more board space is consumed. When changes to parameters such as voltage threshold or reset-timeout period are necessary, a new device may be required. One way to reduce the level of circuitry complexity is to use a digital system management IC that combines monitoring, sequencing and other functions. With programmability, the power management/supervising becomes flexible and more intelligent, and the overall cost and board space are reduced. Moreover, a communication can be established between the power manager and load circuitry or higher-level digital systems.
Today's state-of-the-art control technique for dc-dc converters, however, generally remains analog and is not matched with today's digital power management and powered digital systems. However, digital control has demonstrated certain advantages over analog control, such as reconfiguration flexibility, control adaptability to system variation, low power consumption, high reliability, elimination of component tolerances and ageing, and ease of integration and interface with other digital systems.
In today's dc-dc converters, each controller dedicatedly controls a single dc-dc converter. With the proliferation of dc-dc converters on a single load board, the number of dedicated controllers proportionally increases. With the advance of digital controller technology, dc-dc converters will be able to interface with one another or other digital systems through a communication bus. For example, the dc-dc converters may be controlled by their on-board controllers in response to control commands received over a synchronous serial communication bus. However, the overall cost of the control circuitry goes up with the increased number of controllers, and the communication protocol also becomes a concern.